DEAR DR. BLONZ: Please provide more information about the xanthan gum and cellulose gel that I find in my fat-free salad dressings. I tend to eat a lot of salad, and the dressings taste fine, but is there a reason to be concerned about eating these components on a regular basis? -- S.F., San Jose, California

DEAR S.F.: Dressing provides a flavor accent for the salad components, but to do this effectively, it must provide a light, easily distributed coating, and leave a pleasant mouth-feel. The two ingredients you mentioned serve these purposes in commercially produced dressing.

Xanthan gum is made from a specially fermented cornstarch syrup. It was created in the 1960s at the U.S. Department of Agriculture’s research station in Peoria, Illinois, as part of a project to find new uses for surplus corn. Xanthan gum helps to thicken foods’ texture and stabilize components in a mixture. It has proven to be quite versatile: Aside from salad dressings, it’s used in puddings, sauces, baked goods and desserts. Because it is made from corn, xanthan gum should be avoided by those who are allergic, but aside from that, there do not appear to be any problems associated with its use.

Cellulose gum is made from the fibrous cell walls of plants. It is a naturally occurring thickener used in dressings, ice creams and puddings.

Neither compound brings nutritional assets to the party, but they appear to be quite safe as food additives for use on a regular basis. Always read the rest of the ingredient list and the Nutrition Facts panel to see what else the product has to offer.

DEAR DR. BLONZ: I was surprised to see a dietary supplement proclaim oxygen as one of its active ingredients. How could that work? If it does, would it be a concern that effectiveness diminishes with prolonged use? -- H.B., Walnut Creek, California

DEAR H.B.: Let’s not get ahead of ourselves by assuming effectiveness. Oxygen is essential for carbon-based forms of life due to the many ways that carbon and oxygen can react together, and in the process, absorb or release energy. Oxygen is also involved in other metabolic processes.

The supplement angle makes little sense, as the body is designed to take in and utilize its needed oxygen via a gaseous exchange in the lungs, not as a dietary supplement that comes in through the stomach. This is not a route to deliver oxygen to the body. While there may be legitimate products out there, the Federal Trade Commission has gone after such dubious claims in the past (see tinyurl.com/q9k8cvr).

Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: My parents, now in their 80s, say that they no longer have any real appetite, or at least nothing compared with earlier in life. For them, eating has become more of an obligation and a social event than something driven by hunger. Whenever I eat over at their house, they don’t eat much of anything, especially protein. They have a piece of fish every now and then, but usually split an entree when eating out at a restaurant. They eat vegetables and fruit at most meals, and have cereal with milk or an occasional egg for breakfast.

Like them, I am not a big meat eater, but I know we need protein. How much of a problem is this? -- V.N., Oakland, California

DEAR V.N.: Protein deficiencies are a serious issue in developing countries, where protein foods are scarce and unaffordable, and such deficiencies can be life-threatening. In the U.S. and Canada, however, people tend to eat too much protein, rather than not enough. This being said, your concerns about your parents’ diets are not groundless.

For well-nourished people, occasionally taking in less protein than required will not pose a problem. It only becomes problematic if insufficient protein intake is a regular event. Depending on the length and degree, symptoms of an ongoing protein deficiency could include: increased susceptibility to disease, poor wound healing, fatigue, anemia, hair and skin problems, mental confusion, pallor, digestive disturbances, muscle wasting and weight loss. Many of these are symptoms generally associated with aging.

Surveys have shown that a large proportion of the elderly eat below the recommended dietary allowance (RDA) for protein, with the lowest amount being consumed by the homebound elderly. Such surveys have gone almost unnoticed because the levels involved weren’t very far below the RDA. Some studies have reported that the elderly may actually have higher protein requirements than other adults. Such research raises serious questions as to whether a chronic protein deficiency may be contributing to the decline of the elderly -- more than was previously thought.

The official RDA for adults is 11 grams of protein for every 30 pounds of body weight. This would be about 55 grams of protein for a 150-pound individual. However, a study in the American Journal of Clinical Nutrition reported that individuals over 60 years of age should opt for about 14 to 17 grams of protein per day for every 30 pounds of body weight. By this formula, a 150-pound adult over age 60 should aim for a daily protein intake of 70 to 85 grams per day. (Note: Your ideal body weight -- not necessarily the number you currently see on the scale -- is the one to use. See the calculator at tinyurl.com/y9a4m2gk.)

For reference, there are approximately 30-35 grams of protein in a 4-ounce piece of lean fish, meat or chicken, which is about the size of a pack of playing cards. Protein is also present in nuts, seeds, dairy, grains and legumes. You can view the nutrient content of individual foods using the USDA database at ndb.nal.usda.gov/ndb.

While it is important to get the protein we need, keep in mind that our bodies are not set up to store excess protein for later use. Overindulgence with this relatively expensive type of food causes the body to treat it as excess calories; it becomes fat and gets stored as such. There is no buzzer when we reach our requirements; we have to make ourselves aware of what we consume.

Protein adequacy can become a problem as we age, so think of that big picture, both for your parents and yourself. A healthful approach to protein, fats, carbohydrates, and whole fruits and vegetables should always be the driving element.

Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: I have been trying to cut back on my intake of meat and dairy. I have two young boys, and they are less than enthusiastic. I am wondering if my new vegetarian menu will provide them the protein they need. -- S.T., Arizona City, Arizona

DEAR S.T.: A semi-vegetarian menu, or one where there is no animal food whatsoever (vegan), can easily meet your family’s protein needs. It does depend, though, on which foods you include. You cannot simply eat plant foods without a plan and think you have things covered. A little background on protein may be of assistance.

First, there’s no question that proteins are important in the scheme of things; they are used to make hair, skin, nails, muscles, organs, blood cells, bones, brain and nerve tissue, enzymes, hormones, antibodies, chemical messengers and the DNA and RNA used to form the genetic code of life. Quite a lineup.

While there are different types of protein, they are all made up of the same amino acid building blocks. Our bodies can synthesize many amino acids on their own, but there are some we cannot make, and these have to be supplied by our diets. The ones we need are referred to as the “essential amino acids” (EAAs).

Most foods have some amino acids. Animal proteins, such as meat, fish, eggs and dairy products, are called complete proteins because they usually contain all the EAAs. Vegetable proteins, such as grains and legumes, are considered to be incomplete proteins because they’re missing, or are very low in, one or more EAAs. Soy protein is one exception, in that it is a complete vegetable protein. Vegetarianism revolves around the fact that one can easily meet their daily protein requirement by combining plant foods in a way that provides all the EAAs the body needs.

There are three basic types of vegetable protein: whole grains, such as rice, corn, oats and barley; legumes, such as beans and lentils; and nuts and seeds, such as almonds, sunflower seeds and sesame seeds. By planning the meals for the day to include foods from two or more of these groups, you end up creating a complete protein. For example, by eating rice (grains) and beans (legumes), you supply the body with the EAAs it needs to make its protein. Please note that these complementary foods do not have to be eaten at the same meal.

There is an excellent source page on vegetarianism at the National Library of Medicine, and it includes links to address issues for children and other groups. Find it at tinyurl.com/yd6hzh2a.

Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.